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Old 11-24-2004, 06:09 AM   #1
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Default Bad Power Capacitor???

Some ESCs use external power capacitors. Is there any way to test them to see if they're working properly? Is there any visible way to check them for damage? On my recently purchased Cyclone '99 I notice that when I disconnect my pack if I turn the ESC on the red light comes on for 1 second or so, which I'm assuming means the power capacitor is discharging. Then, when I connect a charged pack there is a tiny spark on the connector, which I'm assuming means the capacitor is charging back up. Is this normal? I have an old Tekin manual for a G-12cIII speedo, which is also the manual for the G-9, that states when power is connected to the G-9, which has internal capacitors, there will be a small spark created. Just curious! Thanks in advance for any info.
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Old 11-24-2004, 06:23 AM   #2
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Your observation about the charging and discharging of the capacitor is correct. As for damage, don't use a dented capacitor or one that looks like it is leaking or "oozing" for lack of a better term. When a capacitor is dented the seperated metal plates can touch and short. If the capacitor is leaking the electrolyte which is the dialectric material seperating the plates can also short making your capacitor a very good resistor.
Travis Lewis
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Old 11-24-2004, 06:30 AM   #3
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Thanks for the reply. My Cyclone is equipped with a 4700uF capacitor and upon recent inspection I noticed the bottom of it was bulged out a little. I made 2 or 3 runs with a stock motor before I noticed it, but the ESC performed fine. I have 2 Novak brand capacitors ordered from e-Bay on the way. I will replace the capacitor before I run the buggy again. Will accidentally using a bad capacitor for a few runs damage an ESC? Thanks again.
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Old 11-24-2004, 10:53 AM   #4
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Sometimes a dead capacitor behaves like a wire so a shortcircuit could happen between the two poles of the battery.

Anyway, a capacitor is a very cheap piece if you buy it in a electronics supplier (radio shack i.e.), not a capacitor from Novak, LRP, Mtroniks.......they just peel off the label and paint it with funny colours.
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Old 11-24-2004, 10:59 AM   #5
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Bulging bottom, bent casing and "crust" around were the wires exit the capacitor is all indication of bad cap.
You can use ohmmeter, depending on the meter, the resistance of the capacitor could start out low but should end as infinite.
There is also a special type of ohmmeter called ESR meter that measures E.quelant S.eries R.esistance (is the name coincidence?) If the capacitor has started to dry out, (there is liquid inside it, when it dries the capacitor becomes useless), then the ESR rises. This meter Here is about 90 dollars including shipping.
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